Transmission rattle when taking off uphill

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I have just picked up my 03 Prado Grande auto. I would reverse down an inclined driveway (about 30 degrees), stop with foot on brake pedal, engage D then step on the accelerator. I then hear a rattle (like the noise of the compressed air drill used to tighten the nuts of a wheel) and the TRC light comes on. The action of releasing the brake causes the car to go back until I step on the accelerator, and then the rattle. The rattle doesn't occur if the handbrake is on and I do a hill start.

Anyone have any ideas?

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Transmission rattle when taking off uphill

I then hear a rattle (like the noise of the compressed air drill used to tighten the nuts of a wheel) and the TRC light comes on.

Sounds like the traction control kicking in to me.... normal noise. Because the vehicle rolls back and you hit the accelerator to go forward I'd say you're spinng a wheel enough for the Traction control to kick in.

Mick

[George_M Junior Member Find all posts View Profile Close George_M]

Re: Transmission rattle when taking off uphill

Yeah - that all sounds normal. I don't think it's wheel spin, rather some sort of "hold" device because the vehicle thinks you're rolling backwards down hill. I can get mine to do this (on the bitumen) at traffic lights near my place, that are near the top of a steep hill. Have you had a look at your vehicle manual?

George_M

[Guest Close Guest]

Re: Transmission rattle when taking off uphill

Hi just to clarify a bit,

If you stop on a hill with the brake on there should be no TRC interaction.

If you then release the brake and the auto can hold the car ie not roll back then there should also be no TRC interaction.

If the car is holding on the auto and your accelerate off then again assuming the wheels aren't loosing traction and spinning then again
there will be no TRC interaction.

If you release then brake on a step hill and the auto can't hold it, ie car starts to roll back the the Uphill assits will kick in
and the brakes will be applied released applied etc to hold the car, the car will still roll back albiet slowly as the brakes engage
release etc, till you press the accelerator pedal then the car should move forward with no noise unless the wheels are loosing
traction in which case the TRC with then kick in.

If the car is holding on the auto and you accelerate with no wheel spin and you get the TRC engaging then you would seem to
have a problem with the TRC.

Cheers

LeighW

[Guest Close Guest]

Re: Transmission rattle when taking off uphill

Thanks for all the replies.

The driveway that I was on is a concrete driveway and it was dry. There was no way that any car could have its wheels spinning under those conditions.

I have read the manual and it only mentions the "VSC TRC" light, as though both VSC and TRC light needs to come on together to indicate that there is a problem. In my case, only the TRC light came on and it was blinking. The rate of blinking seems to be synchronised with the frequency of the rattling sound.

The manual also says that when active traction control is operating on slippery roads, the slip indicator light blinks (and it shows a picture of a car with S-shaped slip marks behind it). This slip indicator light also comes on when the VSC is active. The slip indicator light did NOT come on in my case.

On Monday morning, just before we started our journey from Sydney back to Adelaide, I tried to invoke the problem again but it didn't happen. I reversed down the driveway, step on the brake, engaged to D and let go of the brake. This time, the car held its position (did not roll back) for a second or so and I could go up the driveway with no problems.

Apart from this issue, I have no problems with the transmission of the car. Now that I am in ADL, I need to find a similar driveway to replicate the problem.

[George_M Junior Member Find all posts View Profile Close George_M]

Re: Transmission rattle when taking off uphill

What you describe sounds like normal operation on a hill with the transmission in "drive", the handbrake off, and your foot off the brake.

Have you had a look at the "Hill-start assist control system" in your manual (P156 in mine)?

George

[Guest Close Guest]

Re: Transmission rattle when taking off uphill

I've read the Hill-start assist section in the manual and it states that when the system is operating, the slip indicator light comes on. In my situation, the car rolls back with D engaged and I release the brake pedal. The slip indicator light did not come on but the TRC light came on (blinking) along with the rattling sound.

The manual states that there is a buzzer / alarm under some conditions. What does this buzzer sound like?

[ozwapet2 Advanced Member Find all posts View Profile Close ozwapet2]

Re: Transmission rattle when taking off uphill

It's not a buzz but a beep. In my experience it only beeps when the Vehicle Stability Control ( VSC) is activated.
When TRC activates I only hear the gentle rattling sound from the ABS pump - It's kinda reassuring in a way.

I've neer had the TRC activate on a steep sealed drive - but my driving style might be different to yours amts

This is in a 2008 GXL with option Pack 1 - Grandes might be set up differently, or they may have tweaked the programming since 03.

[Guest Close Guest]

Re: Transmission rattle when taking off uphill

Again, thanks for all the replies

I have taken the car to the dealer I normally do my servicing at and they could not find any error codes nor was there any history of previous codes. They can't really pinpoint or offer an explanation to the issue.

So right now, I'll be looking for a similar driveway to try and replicate the problem. The servicing guys would prefer to see it for themselves for more efficient fault finding.

The fact that it happened on 4 occasions on the same driveway over a period of just 3 days got me worried. The fact that the manual does not mention anything about this rattle got me even more worried.

[Guest Close Guest]

Re: Transmission rattle when taking off uphill

Just an update.

I took the Prado and 2 families (both families in the one Prado) to Saunders Gorge Sanctuary (viewtopic.php?f=29&t=2365&p=90423#p90423). Apparently it is an easy track but not for the beginner. There were a couple of steep hills, one right at the beginning which frightened everyone in the car.

The day went really well and I was conscious of the little problem I spoke about in this thread. I used all the gadgetry I had in the Grande on the 4WD track and I'm glad to report that everything was functioning normally. With DAC on, I can hear the slight ticking noise while the Slip indicator light was blinking. I could also hear the ABS applying the brakes to the wheel. It sounded like metal creaking (like when the Titanic was sinking). As mentioned earlier, there were a couple of steep hill climbs and not once did I hear the rattle and the TRC light coming on. Maybe because it was on low range. At one stage, I think I had the DAC engaged for too long and the alarm came on.

But I'm glad that the 4WD system in the Prado checked out OK as there was no opportunity to test it out during the test drive. Overall, everyone had a great time and can't wait to go back there again. After completing the track, I can see why others say that it was an easy track. It's certainly easy for the Prado but not for the uninitiated driver. We'll be back there sometime soon and will probably stay overnight as the place is just absolutely beautiful in winter.

[Guest Close Guest]

Re: Transmission rattle when taking off uphill

Well I found someone else in the big world wide web with very similar sounding problem.

http://au.toyotaownersclub.com/forums/i ... opic=18858

I guess I'm not quite alone...

[raydhillon Junior Member Find all posts View Profile Close raydhillon]

Re: Transmission rattle when taking off uphill

Well I found someone else in the big world wide web with very similar sounding problem.

http://au.toyotaownersclub.com/forums/i ... opic=18858

I guess I'm not quite alone...

Andrew, i second that. its exactly the same noise i get going up my steep driveway, i also roll back and hear that wierd noise from the pedal. . . ill ask toyota tomorrow booked in for a sovereign bullbar mount replacement and disc machining/ pads. . .